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TXS0108E vs. TXB0108

stan schekall
Prodigy 30 points
Other Parts Discussed in Thread: TXS0108E, TXB0108

I have a design that uses TXS0108E and works well.

Some cards were assembeled  with TXB0108 instesd of the TXS0108E, These cards fail intermitenly.

Can someone explain the conditions where TXB0108 would not work and TXS0108E would work.

 

 

  • 0
    TI__Expert 4705 points

    Hi, Stan,

    The key difference to make TXB0108 not work and TXS0108 work is below.

    TXB0108 is only used for push pull, it can not used at Open drain required, but TXS0108 can work both push pull and open drian.

    So please check whether the transferred signals are Open drian.  any further thing, please let me know.

    BR
    Junjie

  • 0 in reply to Junjie Mai
    Prodigy 70 points

    hi

    I have faced the same issue. One TXS device doesnt worked properly and when replaced , that chip works. TXS can be used for both push-pull and opendrain IO's as per the datasheet.

     

    regards

    Jonna

     

  • 0 in reply to Junjie Mai
    Prodigy 30 points

     

    They are PUSH PULL so I concluded that TXB0108 would work; it does not, whereas the TXS0801 does work. So I'm trying to understand why.

    the conditions are :

    VCCA = 1.8V, VCCB= 5V

    The 1.8V side has a resistive load, I'm not sure how large, but I  estimate somewhere around  3K ohms. (could be wrong)

    The 5V side signals have  a weak pullup (100K)

     

  • 0 in reply to stan schekall
    TI__Expert 4705 points

    Hi, Stan,

    Could you please share your schematic here? also give me the clear information, which port has the issue or all port has the issue? also below things need to be checked. and then we can deep into and see what the issue is.

    1. For TXB0108, it needs the driver at least has 2mA current drive capability.

    2. Measure the Vol and Voh for TXB0108, and the Vih and Vil for TXB0108 to check any margin for the port which had the issue.  also check any pull up or pull down resistor on that IO.

    3. please clarify this " The 1.8V side has a resistive load, I'm not sure how large, but I  estimate somewhere around  3K ohms. (could be wrong) ", I am not sure I understand this, does your schematic have this information?

     

    BR
    junjie